Underground construction works in rock require knowledge on the rock mass in order to take account for the actual conditions. One important source of information is related to geological mapping. Among others geological mapping includes gathering data on (i) geometric properties of the rock surface as well as (ii) spatial orientation information on discontinuities in the rock mass.
The measurement of discontinuities during conventional geological mapping requires manual access to the rock surface. This may need work in hazardous areas. Therefore contact free measuring principles such as Photogrammetry or Laserscanning highly facilitate geological mapping and increase safety.
Knowledge on the rock geometry is furthermore required in performing blasting works both on surface and underground.
The results from contact free measuring systems include three-dimensional measurements (points) from the rock surface ideally combined with visual information as from photos. For geological mapping the acquired rock surfaces require correct scale and correct spatial orientation.
A conventional approach to provide scale and orientation is the use of so-called control points, i.e. known locations in a given coordinate system. Another possibility is the use of objects of known geometry and orientation (marker elements). They are placed on the surface of interest or somewhere in the area of interest. When the surface is acquired by an optical measuring system the marker elements are identified and their known geometry and/or orientation are used to scale and/or orientate the whole surface measurement.
The placement of the marker elements may require working in hazardous areas and may cost additional efforts such as time.
Existing systems for determining and surveying rock, terrain and object surfaces include ShapeMetriX3D and BlastMetriX3D.
DE 101 37 241 A1 discloses an arrangement that records partial views of the object and registers the views in a global coordinate system. The arrangement comprises an image acquisition system, at least one location camera and a computer unit. Markers are optically projected onto the object and acquired by the location camera. The computer unit records the partial views of the object in the global coordinate system using the information of the detected markers.
JP 2003-035536 A discloses a displacement measurement for determining relative displacements of two cross sections, one of a tunnel and one of an excavated cross-section. A camera is provided that is adapted for taking a picture of a facing of the tunnel. Moreover, a picture of the excavated cross-section is taken. Measuring targets and standard points in the respective pictures are compared to each other in order to measure a displacement between the tunnel and the excavated cross-section.